Liquid crystal display device

ABSTRACT

A liquid crystal display device includes a first substrate, a second substrate facing the first substrate, and a liquid crystal layer interposed between the first substrate and the second substrate. The liquid crystal layer includes liquid crystal molecules having a negative dielectric anisotropy, a response speed of about 4.0 ms or less, and a rotational viscosity of about 47 mPa·S to about 75 mPa·S.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a Continuation of U.S. patent application Ser. No.14/519,763, filed on Oct. 21, 2014, and claims priority from and thebenefit of Korean Patent Application No. 10-2014-0055576, filed on May9, 2014, which is hereby incorporated by reference for all purposes asif fully set forth herein.

BACKGROUND

Field

Exemplary embodiments relate to a liquid crystal display device.

Discussion of the Background

In general, a liquid crystal display device includes a first substrateon which pixel electrodes are disposed, a second substrate on which acommon electrode is disposed, and a liquid crystal layer interposedbetween the first and second substrates. The liquid crystal displaydevice controls the transmittance of light through the liquid crystallayer, in accordance with an electric field formed between the pixelelectrodes and the common electrode, thereby displaying a desired image.The liquid crystal display device includes pixels each including onepixel electrode.

In recent years, the liquid crystal display device has been developed todisplay not only a two-dimensional image but also a three-dimensionalimage. To this end, the pixels of the liquid crystal display device needa much faster response time.

The above information disclosed in this Background section is only forenhancement of understanding of the background of the inventive concept,and, therefore, it may contain information that does not constituteprior art.

SUMMARY

Exemplary embodiments provide a liquid crystal display device capable ofbeing operated at a high temperature.

Additional aspects will be set forth in the detailed description whichfollows, and, in part, will be apparent from the disclosure, or may belearned by practice of the inventive concept.

Embodiments of the inventive concept provide a liquid crystal displaydevice including a first substrate, a second substrate facing the firstsubstrate, and a liquid crystal layer interposed between the firstsubstrate and the second substrate. The liquid crystal layer includesliquid crystal molecules having a negative dielectric anisotropy and aresponse speed of about 4.0 ms or less, and the liquid crystal moleculeshave a rotational viscosity of about 47 mPa·S to about 75 mPa·S.

The liquid crystal display device has an improved response speed and ahigh voltage maintaining rate.

The foregoing general description and the following detailed descriptionare exemplary and explanatory and are intended to provide furtherexplanation of the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the inventive concept, and are incorporated in andconstitute a part of this specification, illustrate exemplaryembodiments of the inventive concept, and, together with thedescription, serve to explain principles of the inventive concept.

FIG. 1 is a cross-sectional view showing a liquid crystal display deviceaccording to an exemplary embodiment of the present disclosure.

FIG. 2 is an exploded perspective view showing the liquid crystaldisplay device according to an exemplary embodiment of the presentdisclosure.

FIG. 3 is a cross-sectional view taken along a line I-I′ shown in FIG.2.

FIG. 4 is a plan view showing a liquid crystal display panel accordingto an exemplary embodiment of the present disclosure.

FIG. 5 is a cross-sectional view taken along a line II-II′ shown in FIG.5.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

In the following description, for the purposes of explanation, numerousspecific details are set forth in order to provide a thoroughunderstanding of various exemplary embodiments. It is apparent, however,that various exemplary embodiments may be practiced without thesespecific details or with one or more equivalent arrangements. In otherinstances, well-known structures and devices are shown in block diagramform in order to avoid unnecessarily obscuring various exemplaryembodiments.

It will be understood that when an element or layer is referred to asbeing “on”, “connected to” or “coupled to” another element or layer, itcan be directly on, connected or coupled to the other element or layeror intervening elements or layers may be present. In contrast, when anelement is referred to as being “directly on”, “directly connected to”or “directly coupled to” another element or layer, there are nointervening elements or layers present. Like numbers refer to likeelements throughout. As used herein, the term “and/or” includes any andall combinations of one or more of the associated listed items.

It will be understood that, although the terms first, second, etc. maybe used herein to describe various elements, components, regions, layersand/or sections, these elements, components, regions, layers and/orsections should not be limited by these terms. These terms are only usedto distinguish one element, component, region, layer or section fromanother region, layer or section. Thus, a first element, component,region, layer or section discussed below could be termed a secondelement, component, region, layer or section without departing from theteachings of the present invention.

Spatially relative terms, such as “beneath”, “below”, “lower”, “above”,“upper” and the like, may be used herein for ease of description todescribe one element or feature's relationship to another element(s) orfeature(s) as illustrated in the figures. It will be understood that thespatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures. For example, if the device in thefigures is turned over, elements described as “below” or “beneath” otherelements or features would then be oriented “above” the other elementsor features. Thus, the exemplary term “below” can encompass both anorientation of above and below. The device may be otherwise oriented(rotated 90 degrees or at other orientations) and the spatially relativedescriptors used herein interpreted accordingly.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms, “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “includes”and/or “including”, when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof.

“About” or “approximately” as used herein is inclusive of the statedvalue and means within an acceptable range of deviation for theparticular value as determined by one of ordinary skill in the art,considering the measurement in question and the error associated withmeasurement of the particular quantity (i.e., the limitations of themeasurement system). For example, “about” can mean within one or morestandard deviations, or within ±30%, 20%, 10%, 5% of the stated value.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this invention belongs. It will befurther understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art andwill not be interpreted in an idealized or overly formal sense unlessexpressly so defined herein.

Hereinafter, the present invention will be explained in detail withreference to the accompanying drawings.

FIG. 1 is a cross-sectional view showing a liquid crystal display deviceaccording to an exemplary embodiment of the present disclosure.Referring to FIG. 1, the liquid crystal display device includes a liquidcrystal display panel PNL and a backlight unit BLU.

The backlight unit BLU is disposed under the liquid crystal displaypanel PNL to provide light to the liquid crystal display panel PNL. Thebacklight unit BLU includes light sources LS to emit the light. In FIG.1, the light sources LS are disposed right under the liquid crystaldisplay panel PNL. The number of the light sources LS should not belimited to the number shown in FIG. 1. According to another embodiment,for instance, a single light source LS may be provided. According toanother embodiment, the light sources LS may be provided at one side ofthe liquid crystal display panel PNL. Various light sources, such as apoint light source, a line light source, a surface light source, etc.,may be used as the light source LS.

The liquid crystal display panel PNL displays an image. The liquidcrystal display panel PNL has a rectangular plate shape with two pairsof sides meeting at right angles, and one of the two pairs of sides islonger than the other. In detail, the liquid crystal display panel PNLhas the rectangular plate shape with a pair of long sides and a pair ofshort sides. The liquid crystal display panel PNL includes a firstsubstrate SUB1, a second substrate SUB2 facing the first substrate SUB1,and a liquid crystal layer LCL interposed between the first substrateSUB1 and the second substrate SUB2.

The first substrate SUB1 includes a first base substrate BS1 and a pixelelectrode PE disposed on the first base substrate SUB1. The secondsubstrate SUB2 includes a second base substrate BS2 and a commonelectrode CE disposed on the second base substrate BS2. The pixelelectrode PE and the common electrode CE apply an electric field to theliquid crystal layer LCL in response to voltages applied thereto. In thepresent exemplary embodiment, the electric field is formed in adirection substantially perpendicular to the first and second substratesSUB1 and SUB2, but is not limited thereto. According to anotherembodiment, the electric field may be formed in a directionsubstantially parallel to the first and second substrates SUB1 and SUB2.

Although not shown in FIG. 1, a first alignment layer and a secondalignment layer are respectively disposed on the first and secondsubstrates SUB1 and SUB2. The first and second alignment layers are usedto pre-tilt liquid crystal molecules of the liquid crystal layer LCL andinclude an organic polymer and/or an inorganic polymer. For instance,the first and second alignment layers may include a photosensitivepolymer. The photosensitive polymer includes a compound in which adimerization, cis-trans isomerization, or light-decomposition reactionoccurs when light is radiated thereto, and a directivity is given to thepolymer in accordance with the irradiation direction or polarizationdirection of the light.

The liquid crystal molecules of the liquid crystal layer LCL have anegative dielectric anisotropy. The liquid crystal layer LCL has anematic-isotropic transition temperature (Tni) of about 75° C.

The liquid crystal layer LCL includes about 25 parts by weight % toabout 47 parts by weight % of a neutral liquid crystal, and about 52parts by weight % to about 80 parts by weight % of a polar liquidcrystal, based on the total weight of the liquid crystal layer LCL.

The neutral liquid crystal includes one or more kinds of liquid crystalmolecules represented by the following chemical formula 1, and one ormore kinds of liquid crystal molecules represented by the followingchemical formula 2.

In chemical formulas 1 and 2, R and R′ are each independently an alkylor alkoxy group having 1 to 7 carbon atoms.

In the present exemplary embodiment, the neutral liquid crystal furtherincludes one or more kinds of liquid crystal molecules represented bythe following chemical formula 3.

In chemical formula 3, R and R′ are each independently an alkyl oralkoxy group having 1 to 7 carbon atoms.

The polar liquid crystal includes one or more kinds of liquid crystalmolecules represented by the following chemical formula 4, and one ormore kinds of liquid crystal molecules represented by the followingchemical formula 5.

In chemical formulas 4 and 5, R and R′ are each independently an alkylor alkoxy group having 1 to 7 carbon atoms.

In the present exemplary embodiment, the polar liquid crystal furtherincludes one or more kinds of liquid crystal molecules represented bythe following chemical formula 6, or one or more kinds of liquid crystalmolecules represented by the following chemical formula 7.

In chemical formulas 6 and 7, R and R′ are each independently an alkylor alkoxy group having 1 to 7 carbon atoms.

In the liquid crystal display device according to the present exemplaryembodiment, when a rotational viscosity of the liquid crystal moleculesof the liquid crystal layer LCL increases, a response speed of theliquid crystal molecules becomes faster. A time period in which theliquid crystal molecules are transformed by the electric field isreferred to as a rising time, and a time period in which the transformedliquid crystal molecules return to their original position is referredto as a falling time (Toff). The falling time and the rotationalviscosity satisfy the following equation 1.

$\begin{matrix}{{Toff} \propto \frac{\gamma_{1}d^{2}}{K_{33}}} & {{Equation}\mspace{14mu} 1}\end{matrix}$

In equation 1, “γ₁” denotes the rotational viscosity of the liquidcrystal molecules, “d” denotes a distance between the first substrateand the second substrate, i.e., a cell gap, and “K₃₃” denotes a bendingelastic coefficient.

Table 1 below shows a composition ratio of the liquid crystal layer inthe liquid crystal display device according to exemplary embodiments ofthe present disclosure, and Table 2 below shows the rotational viscosityas a function of a drive temperature according to exemplary embodimentsof the present disclosure.

In Table 1, a liquid crystal display device according to a firstexemplary embodiment includes a liquid crystal having anematic-isotropic transition temperature of about 75° C. A liquidcrystal display device according to a second exemplary embodimentincludes a liquid crystal having a nematic-isotropic transitiontemperature of about 110° C. The liquid crystal display devicesaccording to the first and second exemplary embodiments are manufacturedunder the same conditions, except for the composition ratio of theliquid crystal molecules.

TABLE 1 First Second embodiment embodiment Polar Chemical formula(weight %) (weight %) Neutral liquid crystal

 5 to 10  7 to 13

20 to 25 23 to 29

— 1 to 5 Polar liquid crystal

30 to 35 39 to 47

 5 to 10 10 to 16

25 to 35 —

— 3 to 9

In each of the liquid crystal molecules, R and R′ are independentlyselected from alkyl and alkoxy groups, each having 1 to 7 carbon atoms.

TABLE 2 Rotational viscosity (mPa · S) Drive temperature Firstembodiment Second embodiment 20° C. 115 190 30° C. 71 115 40° C. 47 7550° C. 32 52

As shown in Table 2, the drive temperature is inversely proportional tothe rotational viscosity, and thus, the rotational viscosity isdecreased when the drive temperature is increased. Since the fallingtime is decreased when the rotational viscosity is decreased, theresponse speed of the liquid crystal display device becomes faster.

However, when the rotational viscosity is larger than about 75 mPa·S,the falling time becomes greater than a reference time, e.g., about 4.0ms, at which a user perceives an afterimage. Accordingly, the responsespeed of the liquid crystal display device becomes slower. On thecontrary, when the rotational viscosity is smaller than about 47 mPa·S,the mobility of impurities, e.g., ions, existing in the liquid crystalmolecules increases. Thus, a defect may occur, such as reduction in avoltage maintaining rate. Therefore, the rotational viscosity of theliquid crystal layer in the present exemplary embodiment is in a rangeof about 47 mPa·S to about 75 mPa·S. According to some embodiments, theliquid crystal layer has the rotational viscosity of about 52 mPa·S toabout 75 mPa·S.

The following Table 3 shows the falling time (Toff) as a function of thedrive temperature. In Table 3, the falling time (Toff) is set to 100% inthe case that the falling time is about 4.0 ms during the turn-off ofthe pixel electrode, when the liquid crystal molecules of each of thefirst and second embodiments are driven by the electric field formed bythe pixel electrode and the common electrode. Each value represented inTable 3 indicates a relative value of the falling time when the drivetemperature varies in each of the first and second embodiments.

TABLE 3 Falling time (Toff) Drive temperature First embodiment Secondembodiment 20° C. 146.0 187.7 30° C. 100.0 122.5 40° C. 75.0 85.6 50° C.60.3 64.8

To display the image from which the afterimage is removed, the liquidcrystal display device needs to have a driving speed of about 4.2 ms orless. According to Table 3, the liquid crystal display device accordingto the first embodiment has a driving speed exceeding about 4.0 ms whenthe driving temperature is about 20° C., and has a driving speed lessthan about 4.0 ms when the driving temperature is higher than about 30°C. The liquid crystal display device according to the second embodimenthas a driving speed exceeding about 4.0 ms when the driving temperatureis about 20° C. and about 30° C., and has a driving speed less thanabout 4.0 ms when the driving temperature is higher than about 40° C.

Accordingly, the liquid crystal molecules of the liquid crystal layerare driven at the driving temperature of about 40° C. or more, when thenematic-isotropic transition temperature is about 110° C. or more. Theliquid crystal molecules of the liquid crystal layer are driven at adriving temperature of about 30° C. or more, when the nematic-isotropictransition temperature is about 75° C. or more. In this case, the liquidcrystal display device has a driving speed of about 4.0 ms or less.

Tables 4 and 5 show the voltage maintaining rate as a function of thedriving temperate in the first and second embodiments. The voltagemaintaining rate shown in Table 4 is measured at an applied voltage ofabout 0.1 volts and about 60 Hz, between the pixel electrode and thecommon electrode. The voltage maintaining rate shown in Table 5 ismeasured at an applied voltage of about 0.1 volts and about 3 Hz,between the pixel electrode and the common electrode.

TABLE 4 Voltage maintaining rate (%) Drive temperature First embodimentSecond embodiment 30° C. 99.7 99.8 40° C. 99.7 99.8 45° C. 99.7 99.8 50°C. 99.4 99.7

TABLE 5 Voltage maintaining rate (%) Drive temperature First embodimentSecond embodiment 20° C. 98.7 99.4 30° C. 98.2 99.3 40° C. 97.4 98.9 50°C. 96.1 98.5

In the present exemplary embodiments, the voltage maintaining raterequired to stably drive the image is about 97% or more. As shown inTable 4, the voltage maintaining rate is about 97% or more in the firstand second embodiments. However, as shown in Table 5, the voltagemaintaining rate is about 96% when the drive temperature is about 50°C., in the first embodiment.

Accordingly, the liquid crystal display device according to the firstembodiment may be operated at a drive temperature equal to or less thanabout 50° C. The liquid crystal display device according to the secondembodiment may be operated at the drive temperature of less than about50° C.

The liquid crystal display devices having the above-mentionedconfiguration may have fast response speeds and high voltage maintainingrates.

In the present exemplary embodiments, the liquid crystal layer LCL maybe operated in a vertical alignment mode, and in this case, the liquidcrystal molecules of the liquid crystal layer LCL may be liquid crystalmolecules having negative dielectric anisotropy. When the liquid crystalmolecules of the liquid crystal layer LCL have negative dielectricanisotropy, the liquid crystal molecules are aligned in a directionsubstantially perpendicular to surfaces of the first and secondsubstrates SUB1 and SUB2, when no electric field is applied to theliquid crystal molecules, and are aligned in a direction substantiallyin parallel to the surfaces of the first and second substrates SUB1 andSUB2 when an electric field is applied to the liquid crystal molecules.

According to various embodiments, provided is a liquid crystal displaydevice that may include the vertical alignment liquid crystal molecules.FIG. 2 is an exploded perspective view showing the liquid crystaldisplay device operated with the vertical alignment mode, and FIG. 3 isa cross-sectional view taken along a line I-I′ shown in FIG. 2.Referring to FIGS. 2 and 3, the liquid crystal display device includesthe liquid crystal display panel PNL and the backlight unit.

The liquid crystal display panel PNL displays an image. The liquidcrystal display panel PNL includes the first substrate SUB1, the secondsubstrate SUB2 facing the first substrate SUB1, and the liquid crystallayer (not shown) interposed between the first substrate SUB1 and thesecond substrate SUB2. The first substrate SUB1 has an area larger thanthat of the second substrate SUB2, and thus, one side of the firstsubstrate SUB1 is not overlapped with the second substrate SUB2.

According to the present exemplary embodiment, the first substrate SUB1includes pixel electrodes (not shown) and thin film transistors (notshown) electrically connected to the pixel electrodes in a one-to-onecorrespondence. Each thin film transistor switches a driving signalapplied to a corresponding pixel electrode of the pixel electrodes. Thesecond substrate SUB2 includes the common electrode (not shown) thatforms the electric field in cooperation with the pixel electrodes, tocontrol the alignment of the liquid crystal molecules of the liquidcrystal layer. The liquid crystal display panel PNL drives the liquidcrystal molecules of the liquid crystal layer to display the image in afront direction.

The liquid crystal display panel PNL includes a tape carrier package TCPand a printed circuit board PCB electrically connected to the liquidcrystal display panel PNL through the tape carrier package TCP. Adriving circuit, e.g., a drive IC, is mounted on the tape carrierpackage TCP.

The tape carrier package TCP is attached to the end of the firstsubstrate SUB1 that is not covered by the second substrate SUB2. For theconvenience of explanation, the printed circuit board PCB is disposed atthe same plane as the liquid crystal display panel PNL in FIG. 2.However, the printed circuit board PCB is substantially disposed on anouter surface of a bottom chassis BC, as shown in FIG. 3. In this case,the tape carrier package TCP is bent along the outer surface of thebottom chassis BC. Thus, the liquid crystal display panel PNL isconnected to the printed circuit board PCB.

The backlight unit provides the light to the liquid crystal displaypanel PNL. The backlight unit includes a mold frame MF to support theliquid crystal display panel PNL, the light source LS to emit the light,a light guide plate LGP to guide the light, optical sheets OPS disposedon the light guide plate LGP, a reflection sheet RS disposed under thelight guide plate LGP, and the bottom chassis BC disposed under thereflection sheet RS.

The mold frame MF is provided along the edges of the liquid crystaldisplay panel PNL to support the liquid crystal display panel PNL. Themold frame MF may include a fixing member, e.g., a catching jaw, to fixor support the light source LS and the optical sheets OPS. The moldframe MF is provided to correspond to four sides of the display panel DPor at least a portion of the four sides. For instance, the mold frame MFhas a rectangular shape to correspond to the four sides of the displaypanel DP, or may have a U shape to correspond to three sides of thedisplay panel DP. The mold frame MF may be integrally formed as a singleunit or may formed in plural parts to be assembled to each other at alater stage. The mold frame MF includes an organic material, e.g.,polymer resin, but is not limited thereto.

The light source LS may be a point light source, a line light source, ora surface light source, but is limited thereto. The light guide plateLGP is disposed under the liquid crystal display panel PNL to guide thelight emitted from the light source LS to the liquid crystal displaypanel PNL.

The optical sheets OPS are disposed between the light guide plate LGPand the liquid crystal display panel PNL. The optical sheets OPS controlthe properties of light exiting the light guide plate LGP. The opticalsheets OPS include a diffusion sheet DS, a prism sheet PS, and aprotection sheet PRS, which are sequentially stacked on the light guideplate LGP.

The reflection sheet RS is disposed under the light guide plate LGP toreflect the light leaked from the light guide plate LGP, without beingdirected to the liquid crystal display panel PNL, towards the liquidcrystal display panel PNL.

A top chassis TC is disposed on the liquid crystal display panel PNL.The top chassis TC supports the front of the liquid crystal displaypanel PNL and covers a side portion of the mold frame MF, or a sideportion of the bottom chassis BC. The top chassis TC includes a displaywindow WD to expose an area of the liquid crystal display panel PNL.

The bottom chassis BC is disposed under the reflection sheet RS toaccommodate the liquid crystal display panel PNL, the mold frame MF, thelight source LS, the light guide plate LGP, the optical sheets OPS, andthe reflection sheet RS.

FIG. 4 is a plan view showing a pixel of the liquid crystal displaypanel, according to an exemplary embodiment of the present disclosure,and FIG. 5 is a cross-sectional view taken along a line II-II′ shown inFIG. 4. Referring to FIGS. 4 and 5, the liquid crystal display deviceincludes a first substrate SUB1, a second substrate SUB2 facing thefirst substrate SUB1, and a liquid crystal layer LCL interposed betweenthe first substrate SUB1 and the second substrate SUB2.

The first substrate SUB1 includes a first base substrate BS1, gatelines, data lines, a plurality of pixels, and a first alignment layerALN1.

The first substrate SUB1 includes pixel areas arranged in a matrix, andthe pixels are arranged in the pixel areas in a one-to-onecorrespondence. For the convenience of explanation, FIG. 5 shows onepixel PXL, an n-th gate line GLn of the gate lines, and an m-th dataline DLm of the data lines, which are arranged in one pixel area, sincethe pixel areas have the same structure. Hereinafter, the n-th gate lineGLn and the m-th data line DLm will be referred to as a gate line and adata line.

The gate line GLn is disposed on the first base substrate BS1 andextends in a first direction D1. The data line DLm is disposed on thegate line GLn, such that a gate insulating layer GI is disposed betweenthe gate line GLn and the data line DLm. The data line DLm extends in asecond direction D2 crossing the first direction D1. The gate insulatinglayer GI is disposed over the entire surface of the first base substrateBS1 to cover the gate line GLn.

The pixel PXL is connected to a corresponding gate line GLn of the gatelines and a corresponding data line DLm of the data lines. The pixel PXLincludes a thin film transistor Tr, a pixel electrode PE connected tothe thin film transistor Tr, and a storage electrode part.

The thin film transistor Tr includes a gate electrode GE, asemiconductor layer SM, a source electrode SE, and a drain electrode DE.

The gate electrode GE is protruded from the gate line GLn or disposed ona portion of the gate line GLn.

The gate line GLn and the gate electrode GE are formed of a metalmaterial. The gate line GLn and the gate electrode GE may includenickel, chromium, molybdenum, aluminum, titanium, copper, tungsten, oran alloy thereof. The gate line GLn and the gate electrode GE may have asingle-layer structure or a multi-layer structure of the above-mentionedmetal materials. For instance, the gate line GLn and the gate electrodeGE have a triple-layer structure of molybdenum, aluminum, andmolybdenum, which are sequentially stacked on one another, adouble-layer structure of titanium and copper sequentially stacked, or asingle-layer structure of an alloy of titanium and copper.

The gate insulating layer GI is disposed over the first base substrateBS1 to cover the gate electrode GE. The semiconductor layer SM isprovided on the gate insulating layer GI. The semiconductor layer SM isdisposed on the gate electrode GE, such that the gate insulating layerGI is disposed between the semiconductor layer SM and the gateelectrode. The semiconductor layer SM includes an active pattern (notshown) disposed on the gate insulating layer GI and an ohmic contactlayer (not shown) disposed on the active pattern. The active patternincludes an amorphous silicon thin film layer, and the ohmic contactlayer includes n+ amorphous silicon thin film layer. The ohmic contactlayer allows the active pattern to be in ohmic contact with the sourceelectrode SE and the drain electrode DE.

The source electrode SE is branched from the data line DLm. The sourceelectrode SE is disposed on the ohmic contact layer and a portion of thesource electrode SE is overlapped with the gate electrode GE.

The drain electrode DE is spaced apart from the source electrode SE,such that the semiconductor layer SM is disposed between the drain andsource electrodes DE and SE. The drain electrode DE is disposed on theohmic contact layer and a portion of the drain electrode DE isoverlapped with the gate electrode GE.

The source electrode SE and the drain electrode DE may be formed of aconductive material, e.g., a metal material, such as nickel, chromium,molybdenum, aluminum, titanium, copper, tungsten, or an alloy thereof.Each of the source electrode SE and the drain electrode DE may have asingle-layer structure or a multi-layer structure. For example, each ofthe source and drain electrodes SE and DE may have a double-layerstructure of titanium and copper sequentially stacked one on another, ora single-layer structure of an alloy of titanium and copper.

An upper surface of the active pattern is exposed between the sourceelectrode SE and the drain electrode, and a channel portion is formedbetween the source electrode SE and the drain electrode DE as aconductive channel according to the application of the voltage to thegate electrode GE. The source electrode SE and the drain electrode DEare overlapped with the portion of the semiconductor layer SM, exceptfor where the channel portion is formed.

The storage electrode part includes a storage line SLn extending in thefirst direction D1 and first and second branch electrodes LSLn and RSLnbranched from the storage line SLn and extending in the second directionD2.

The pixel electrode PE is connected to the drain electrode DE through acontact hole CH formed through a passivation layer PSV disposed betweenthe pixel electrode PE and the drain electrode DE. The pixel electrodePE is partially overlapped with the storage line SLn and the first andsecond branch electrodes LSLn and RSLn, to form a storage capacitor.

The passivation layer PSV covers the source electrode SE, the drainelectrode DE, the channel portion, and the gate insulating layer GI. Thepassivation layer PSV includes the contact hole CH exposing a portion ofthe drain electrode DE. The passivation layer PSV includes siliconnitride or silicon oxide. The pixel electrode PE is connected to thedrain electrode DE through the contact hole CH formed through thepassivation layer PSV.

The pixel electrode PE includes a first domain divider PEDD to dividethe pixel PXL into plural domains. The first domain divider PEDD may bea cut-away portion formed by patterning the pixel electrode PE or aprotrusion thereof. The cut-away portion may be an opening formed byremoving a portion of the pixel electrode PE or may be a slit formedtherein. The first domain divider PEDD includes a horizontal portionand/or a vertical portion, which extend(s) in the first direction D1 orthe second direction D2, to divide the pixel PXL into two parts in alongitudinal direction. The first domain divider PEDD includes obliqueline portions inclined with respect to the first and second directionsD1 and D2. An oblique line portion disposed at one side of thehorizontal portion is substantially linearly symmetrical with an obliqueline portion disposed at the other side of the horizontal portion, withrespect to the horizontal portion.

The pixel electrode PE includes a transparent conductive material. Inparticular, the pixel electrode PE includes a transparent conductiveoxide, e.g., indium tin oxide, indium zinc oxide, indium tin zinc oxide,etc.

The first alignment layer ALN1 is disposed on the pixel electrode PE toalign the liquid crystal molecules of the liquid crystal layer LCL. Thesecond substrate SUB2 includes a second base substrate BS2, a commonelectrode CE, and a second alignment layer ALN2.

The common electrode CE is disposed on the second base substrate BS2 andforms the electric field in cooperation with the pixel electrode PE, todrive the liquid crystal molecules of the liquid crystal layer LCL. Thecommon electrode CE includes a transparent conductive material. Indetail, the common electrode CE includes a transparent metal oxide,e.g., indium tin oxide, indium zinc oxide, indium tin zinc oxide, etc.

The common electrode CE includes a second domain divider CEDD to dividethe pixel PXL into plural domains. The second domain divider CEDD may bea cut-away portion formed by patterning the common electrode CE or maybe a protrusion. The cut-away portion may be an opening formed bypartially removing a portion of the common electrode CE. The seconddomain divider CEDD includes a horizontal portion and/or a verticalportion, which extend(s) in the first direction D1 or the seconddirection D2 to divide the pixel PXL into two parts in the longitudinaldirection. The second domain divider CEDD includes oblique line portionsinclined with respect to the first and second directions D1 and D2. Anoblique line portion disposed at one side of the horizontal portion issubstantially linearly symmetrical with an oblique line portion disposedat the other side of the horizontal portion, with respect to thehorizontal portion.

The horizontal portion of the first domain divider PEDD and thehorizontal portion of the second domain divider CEDD may be disposed atthe same position. The oblique line portion of the first domain dividerPEDD and the oblique line portion of the second domain divider CEDD maybe arranged substantially in parallel to each other. In addition, theoblique line portion of the first domain divider PEDD and the obliqueline portion of the second domain divider CEDD may be alternatelyarranged with each other.

The second alignment layer ALN is disposed on the common electrode CE toalign the liquid crystal molecules of the liquid crystal layer LCL. Theliquid crystal layer LCL including the liquid crystal molecules isdisposed between the first substrate SUB1 and the second substrate SUB2.

When a gate signal is applied to the gate line GLn, the thin filmtransistor Tr is turned on. Therefore, a data signal applied to the dataline DLm is applied to the pixel electrode PE through the turned-on thinfilm transistor Tr. When the data signal is applied to the pixelelectrode PE through the thin film transistor Tr, the electric field isformed between the pixel electrode PE and the common electrode CE. Theliquid crystal molecules are driven in response to the electric fieldformed by a difference in voltage between the voltage applied to thepixel electrode PE and the voltage applied to the common electrode CE.Thus, the amount of the light passing through the liquid crystal layerLCL is changed, so that a desired image is displayed through the liquidcrystal display device.

In the present exemplary embodiment, the vertical alignment mode liquidcrystal display device including the above-mentioned domain dividers hasbeen described as the liquid crystal display device, but the liquidcrystal display device is not limited to the vertical alignment modeliquid crystal display device including the above-mentioned domaindividers. That is, the liquid crystal display device according to thepresent disclosure may be a vertical alignment liquid crystal displaydevice including an electrode through which the slit is formed or avertical alignment liquid crystal display device including an electrodethrough which a plurality of micro-slits is formed, which aresubstantially in parallel to each other.

Although exemplary embodiments of the present invention have beendescribed, it is understood that the present invention should not belimited to these exemplary embodiments but various changes andmodifications can be made by one ordinary skilled in the art within thespirit and scope of the present invention as hereinafter claimed.

What is claimed is:
 1. A liquid crystal display device, comprising: afirst substrate; an opposing second substrate; and a liquid crystallayer interposed between the first substrate and the second substrate,the liquid crystal layer consisting of: liquid crystal moleculesrepresented by Chemical Formula 1 in an amount of 7% by weight to 13% byweight of the liquid crystal layer; liquid crystal molecules representedby Chemical Formula 2 in an amount of 23% by weight to 29% by weight ofthe liquid crystal layer; liquid crystal molecules represented byChemical Formula 3 in an amount of 1% by weight to 5% by weight of theliquid crystal layer; liquid crystal molecules represented by ChemicalFormula 4 in an amount of 39% by weight to 47% by weight of the liquidcrystal layer; liquid crystal molecules represented by Chemical Formula5 in an amount of 10% by weight to 16% by weight of the liquid crystallayer; liquid crystal molecules represented by Chemical Formula 7 in anamount of 3% by weight to 9% by weight of the liquid crystal layer;wherein Chemical Formulas 1, 2, 3, 4, 5, and 7 are as follows:

wherein, in Chemical Formulas 1, 2, 3, 4, 5, and 7, R and R′ are eachindependently an alkyl or an alkoxy group having 1 to 7 carbons.
 2. Theliquid crystal display device of claim 1, wherein the liquid crystallayer has a nematic isotropic transition temperature of 110° C. or more.3. The liquid crystal display device of claim 1, wherein the liquidcrystal layer has a rotational viscosity of 52 mPa·S to 75 mPa·S whenoperating at a temperature between 40° C. and 50° C.
 4. The liquidcrystal display device of claim 1, wherein the liquid crystal moleculesof the liquid crystal layer have a negative dielectric anisotropy. 5.The liquid crystal display device of claim 1, wherein the liquid crystallayer is configured to operate in a vertical alignment mode.
 6. A liquidcrystal display device, comprising: a first substrate; an opposingsecond substrate; and a liquid crystal layer interposed between thefirst substrate and the second substrate, the liquid crystal layerconsisting of: liquid crystal molecules represented by Chemical Formula1 in an amount of 7% by weight to 13% by weight of the liquid crystallayer; liquid crystal molecules represented by Chemical Formula 2 in anamount of 23% by weight to 29% by weight of the liquid crystal layer;liquid crystal molecules represented by Chemical Formula 3 in an amountof 1% by weight to 5% by weight of the liquid crystal layer; liquidcrystal molecules represented by Chemical Formula 4 in an amount of 39%by weight to 47% by weight of the liquid crystal layer; liquid crystalmolecules represented by Chemical Formula 5 in an amount of 10% byweight to 16% by weight of the liquid crystal layer; liquid crystalmolecules represented by Chemical Formula 7 in an amount of 3% by weightto 9% by weight of the liquid crystal layer; wherein the liquid crystallayer is configured to operate at a temperature of 40° C.±10%; whereinChemical Formulas 1, 2, 3, 4, 5, and 7 are as follows:

wherein, in Chemical Formulas 1, 2, 3, 4, 5, and 7, R and R′ are eachindependently an alkyl or an alkoxy group having 1 to 7 carbons.
 7. Theliquid crystal display device of claim 6, wherein the liquid crystallayer has a nematic isotropic transition temperature of 110° C. or more.8. The liquid crystal display device of claim 6, wherein the liquidcrystal layer has a rotational viscosity of 75 mPa·S.
 9. A liquidcrystal display device, comprising: a first substrate; an opposingsecond substrate; and a liquid crystal layer interposed between thefirst substrate and the second substrate, the liquid crystal layerconsisting of: liquid crystal molecules represented by Chemical Formula1 in an amount of 7% by weight to 13% by weight of the liquid crystallayer; liquid crystal molecules represented by Chemical Formula 2 in anamount of 23% by weight to 29% by weight of the liquid crystal layer;liquid crystal molecules represented by Chemical Formula 3 in an amountof 1% by weight to 5% by weight of the liquid crystal layer; liquidcrystal molecules represented by Chemical Formula 4 in an amount of 39%by weight to 47% by weight of the liquid crystal layer; liquid crystalmolecules represented by Chemical Formula 5 in an amount of 10% byweight to 16% by weight of the liquid crystal layer; liquid crystalmolecules represented by Chemical Formula 7 in an amount of 3% by weightto 9% by weight of the liquid crystal layer; wherein the liquid crystallayer has a nematic isotropic transition temperature of 110° C. or more,wherein the liquid crystal layer has a rotational viscosity of 52 mPa·Sto 75 mPa·S when operating at a temperature of 40° C. to 50° C. andcomprises liquid crystal molecules having a negative dielectricanisotropy, and wherein Chemical Formulas 1, 2, 3, 4, 5, and 7 are asfollows:

wherein, in Chemical Formulas 1, 2, 3, 4, 5, and 7, R and R′ are eachindependently an alkyl or an alkoxy group having 1 to 7 carbons.